Water Management
Environmental monitoring in unregulated rivers
The term 'unregulated river' applies to rivers without major storages, or dams, as well as to rivers where the storages do not release water downstream (in these cases, water is piped to where it is needed, such as metropolitan centres).
A large number of unregulated rivers are covered by water sharing plans and it is hoped that by 2011, all will be. These unregulated rivers are monitored to determine whether the environmental flow rules in the plans are benefiting the environment.
Project aims
The first aim of ecological monitoring in unregulated rivers is to determine whether the environmental objectives of the water sharing plans are being achieved. The objectives of the plans are diverse, but most intend to maintain or improve the ecological condition of the river.
The second aim is to demonstrate how achievement (or non-achievement) of these objectives is related to the plan strategies. For example, other factors – climate change, land use, etc – may affect the condition of a river, and monitoring programs need to be able to discriminate between plan and non-plan related impacts.
Design challenges in monitoring unregulated rivers
The environmental water provisions in the unregulated river water sharing plans are different to those in the regulated rivers. Generally, in unregulated rivers the environmental flow rules consist mainly of annual extraction limits and cease to pump levels which prevent pumping when the river flow drops below a specified level.
The protection of these low flows is important to the survival of many aquatic species.
Our understanding of hydrology and water extraction is also limited in unregulated streams, so we tend not to use a predictive modelling approach so often employed when monitoring regulated rivers. Instead, we compare randomly chosen sites on the river affected by water extraction with physically matched reference sites on rivers unaffected by extraction (known as 'positive' reference sites). The use of reference sites enables changes due to plan implementation to be distinguished from natural changes and changes due to other human influences.
Selection of attributes for monitoring
Measuring trends in attributes with respect to reference conditions is the main way in which the benefits of the environmental rules will be monitored and it is vital that the right ones are selected. To refine the selection process, we make use of conceptual models One such conceptual model is shown below, illustrating how an attribute such as tadpoles can be logically selected by following the linkages through the ecosystem.
Conceptual model: Ecosystem responses to upstream water extraction in rivers under medium–flow and high-flow conditions (freshes and floods). Responses will vary with natural discharge patterns and the timing, frequency and magnitude of extraction.
No matter what attributes are selected, they must have:
- Relevance: Attributes must be relevant to the various types of environment, flow classes and ecosystem properties included in the objectives of the plans.
- Sensitivity: Attributes must be relevant to the various types of environment, flow classes and ecosystem properties included in the objectives of the water sharing plans.
- Practicality: Attributes must be measurable in a repeatable and representative manner with the resources that are likely to be available.
- Interpretability: It must be feasible to distinguish the response of the attributes to water extraction, and ideally to plan strategies, from their responses to other factors.
For more details on the framework and design of the monitoring program, see Program framework for ecological monitoring and reporting of water sharing plans for unregulated rivers – scoping paper (PDF 1.1MB).